I have to admit, all of my carry and use of a Buck 110 years ago made it second nature to open/close it two-handed. The assurance of it's solid lockback was - and still is - worth it. I also have to admit, my ZT-0551s and 0561 seem certainly easier - one-handers, for sure. Knives like that simply were not available when I lusted over - then bought - my first 110.
Now, a modern lockback, as in my only Spyderco's - the Native 4 and 5 models - is centrally located on the back - easier to one-hand close (The Spydie thumbhole makes them an easy one-hand opener, too.). Give one a try... you might just like it!
Stainz